1. Field of the Invention
The present invention relates generally to a cassette containing a recording medium and, more specifically, to a tape cassette for holding a magnetic tape that is provided with a slider capable of movement in the direction of thickness of the case of the cassette that can be manually set to prevent information recorded on the tape from being erroneously erased.
2. Description of the Background
Most tape cassettes are provided with some means for protecting recorded information from erroneous erasing. One such tape cassette is provided with an erase preventive lug as the erroneous erase preventive device, which erase preventive lug is broken and removed after information is recorded on the tape. The drawback in such previously proposed device is that because the broken erase preventive lug cannot be restored to the tape cassette, another member must be attached to the tape cassette in place of the erase preventive lug at the position that had previously been occupied by the erase preventive lug when it is desired to record new signals on the tape in the tape cassette.
Japanese Patent Laid-open (Kokai) No. Hei 1-102788 discloses a tape cassette provided with an erase prevention slider capable of moving between an eras enable position and a write protect position and is provided with first and second protrusions protruding in opposite directions that deviate from the direction of sliding of the slider. The cassette case is provided with a slider receiving hole provided with first and second recesses in the edge thereof. The slider is held at a first position with its first protrusion received in the first recess of the case or at a second position with its second protrusion received in the second recess of the case to set the tape cassette in the erase enable state or the write protect state, respectively.
Thus, the tape cassette can repeatedly be set for the erase enable state or the write protect state by shifting the slider alternately in opposite directions, and the slider can securely be held in place by the engagement of the first recess and the first protrusion or by the engagement of the second recess and the second protrusion. In the case, however, when neither the first protrusion nor the second protrusion of the slider is received in the corresponding recess, that is, in a transitional position when both the first and second protrusions of the slider are on the inner surface of the slider receiving hole of the case, there is a high pressure acting on the slider. Because of this pressure, the slider is difficult to move and hence the slider must be pushed hard in order to shift it, which effort may possibly damage the slider and the case of the tape cassette. This also makes the tape cassette containing the erroneous erasure preventing device difficult to handle.